It depends on how well it's built as well.
If it's too purpose built for the rocks, the highway drivability starts to suffer in terms of noise, rattles, heat, speed, and gear carrying. If the person building the Toyota keeps a good balance between very capable and comfortable long distance on highway and dirt then it's not too far off the deep end.
Basic concept includes:
- Skid Plates/sliders/metal bumper with recovery points
- Soft flexy suspension that can carry 500-700LBS of gear
- Beadlocks
- Winch
- Aux lighting for super dark wet roads/unmaintained roads/trails
- One locker min.
- Ability to carry: tools, fuel, spare parts, gear, hi-lift, recovery gear, roof top tent, skis, another passanger
- Heat
- Able to maintain highway speed
- There's more to this but this is the basic idea
This is on top of a solid foundation which is mechanical, electrical, frame, etc.
Is it comfortable, is it quiet (noise will drain you), is it mechanically sound, can it drive on the highway without any issues, can it stop really well, will it sag out if you put more than 200LBS in the bed, etc...
Again no one says you have to have just one though